Control device



Fb. 12, 1946. c. G. HKRONMILLER 2,394,920

CONTROL DEVICE Filed Dec. 4, 1942 3 Sheets-Sheet 1 attorney Feb. 12, 1946. c. G.\KRONM|LL.ER

CONTROL DEVICE Filed Dec. 4, 1942 s Shets-Sheet s JmBentor (Iii 6 [FUN/VILLA)? ggggzq" //7//////// attorney Patg ted Felt, 12, 1946 Rlsissuso Cari G. Kronmiller, Minneapolis,

Minn., assignor g to Minneapolis-Honeywell Regulator Company,

Minneapolis Minna, a corporation of Delaware Application December 4, 1942, Serial N .467,882 J 23 Claims.

My invention relates to condition responsive switches and more particularly to a switch responsive to variations in temperature adapted among other uses for room temperature control.

Another object of my invention is to provide a novel compact temperature responsiv control mechanism for mounting within a circular convex shaped switch housing.

Another object of myinvention is to provide a pair of thermally responsive bimetallic strips mounted on a pivotal member and arranged so as to jointly control the actuation of a switch member and thus permitting the compact mounting of a thermally responsive mechanism within a circular shaped housing without sacrificing eiliciency of operation.

Another object of my invention is to provide a novel cam arrangement for adjustabiy positioning one of the thermally responsive strips so as to cause in turn the adjustment of the other of the said strips with respect to the switch member so as to regulate the thermal condition value at which said switch maybe actuated.

Another object a novel switch blade structure including a resilient switch blade so constructed as to perform the double function of biasing the said pivotally mounted thermal a direction so as metallic strip to while serving as a tacting means.

Another object is to provide a thermally responsive bimetallic strip actuating means and switch contacts actuated thereby mounted separately and apart from the bimetallic strip so as to provide practically no metallic connections between the contacts and the bimetallic strip actuating means for the better alignment of the contacts.

Another object of my invention is to provide novel compact auxiliary heating mechanism positioned within the concave interior of the convex housing so as to affect equally the pair of bimetallic elements and the said heater controlled responsive bimetallic strips in operatively engage said cam novel push-back resilient conof my invention is to provide to cause the cam actuated biby the said switching mechanism in such a manher as to anticipate the medium called for by the mechanism.

Another object of the invention is the provision of a novel heat damper and deflector mounted upon the heater in such a manner as to better regulate the flow of heat to the thermally responsive element so as to more accurately anticiarrival of a heating thermally responsive I broad general pate the arrival of the heating medium called for by the thermally responsive mechanism.

A further object of my invention isto provide a rotatable adjustment means mounted at the apex of the convex shaped positioned flush with the surface thereof providing a convenient means for adjustment of the said cam for regulating the thermal condition value at which saidswitch may be actuated.

Another object of my invention is to provide a novel adjustment ring mounted within the convex surface of the housing in. combination with mechanical means for regulating the condition value at which said thermally responsive switch mechanism may be actuated.

Condition responsive switch mechanisms provided for mounting within the home and heretofore known in the prior art have invariably included numerous projecting parts and sharp edges which have constituted a certain hazard in the home particularly where there may be children who might while in playing strike against such sharp edges to their injury. It has therefore been an object of my invention to provide a unitary condition responsive mechanism mounted within a circular shaped convex housing and including manually operable means mounted within the surface of the housingfor the convenient finger tip adjustment of the condition value at which said mechanism may be actuated, and such housing and adjustment means having substantially no projecting parts or sharp edges sons thereby to provide a safe construction for mounting within the home.

Other objects and advantages of this invention are set forth in the following description, taken with the accompanying drawings, and the novel features thereof are pointed out in the appended claims. The disclosure, however, is

details, especially in matters of shape, size, andarrangements of parts within the principles of the invention, to the ful1 extent indicated by the the appended claims are expressed.

In the accompanying drawings, wherein like reference characters indicate corresponding parts in the various figures:

Figure 1 is a top p an view of my control mechanism cover;

Figure 2 is a top plan view of a modified form of cover for housing my control mechanism;

Figure 3 is an enlarged top plan view of the control mechanism with the cover of Figure 1 removed;

switch housing and meaning of the terms in which i base member |2 formed of Figure 4 is a sectional view taken along the lines 4-4 of Figure 3 with the cover in place and looking in the direction of the arrows;

Figure 5 is a sectional view taken along the lines 6-! of Figure 3 and looking in the direction of the arrows and with a portion of the switch actuating arm broken away in order to better illustrate the operation thereof;

Figure 6 is an end view of the thermostatic control mechanism which for clarity is shown separately from the remaining parts of the device.

Figure 7 is an enlarged central sectional view of the modified form of my invention shown in Figure 2 but looking at the thermostatic control mechanism in the opposite direction from that shown at Figure 4, and

Figure 8 is a schematic view of a control circuit embodying the control switch mechanism of my invention.

Referring now to the drawings, particularly Figures 3, 4 and 5, the switch actuating mechanism is shown as comprising a pair of U-shaped bimetallic elements or member and 2, which are affixed to a bracket member 3. At opposite ends of the bracket member 3 as shown in Figure Gare projecting ears 4 and 5 which are pivotally connected by rod 6 to correspondingly projecting ears I and 8 of a fixed bracket 9. e fixed bracket 8 is fastened by bolts I and H to a suitable insulating material.

At an end of the bimetallic member I there is provided a slot i3 within which is formed a screwthreaded aperture H for engagement with an adjustment screw l5. An end of the adjustment screw l rides along the cam surface it of an adjustable cam member ll. The cam surface is inclined so as to adiustably pivot the bimetallic member and accordingly the bimetallic member 2 on the rod 5. Adjustable screw I5 is held in engaging relation against the inclined surface of cam under a biasing force which will be explained.

The bimetallic members and 2 are arranged so that the high expansion portion of the member is reversed with respect to the high expansion portion of the member 2. Thus in Figure 3 the high expansion side of the bimetallic member is the upper side while the high expansion side of the bimetallic member 2 is the under side. Therefore upon an increase in temperature the bimetallic member I having the free end thereof fixed as explained by the cam surface It, will rotatably move the bracket 3 in a counterclockwise direction as viewed in Figure 4, in response to such increase in temperature and thereby move the bimetallic member 2 so as to cause the free end thereof to separate the contacts of a switch mechanism as will be explained later. Further since the under side of the bimetallic member 2 is the high expansion side as the bimetallic member 2 warps due to an increase in temperature it will also move its free end in a direction so as to separate the contacts of the said switch mechanism. It will be readily seen that the effects of these two bimetallic members are cumulative and the total movement of the free end of the bimetallic member 2 is substantially the same as if a, single bimetallic member were used of a length equal to the sum of the lengths of the two U-shaped bimetallic members I and 2. It will be readily apparent, moreover, that by arranging the pair of bimetallic member as described and forming the members in a U-shape the same may be conveniently confined in a very to the shaft |8 by a screw 23.

' with. One end of the pin III is limited space while retaining the substantial operative effectiveness of a single bimetallic strip of length equal to the sum of the lengths of the two members.

As shown in Figures 3 and 4, there is fixedly mounted on the cam H a shaft ll connected through the tongue members It and 20 to an adjustable disk like member 2|. The outer surface of adjustable disk 2| is converted and substantially flush with a. convexed outer housing casing 22. As shown in Figure 4, the adjustable disk 2| is positioned within an annular aperture formed at the apex of housing 22 and cam may be conveniently adjusted by the rotation of disk 2|. The disk 2| may be further fastened A rotatable pin ill projects through a suitable aperture positioned in the base member l2 at a point concentric thereafllxed to the cam l1 and shaft l8 at a point concentric with the shaft l8 while the opposite end of the pin I0 is rotatably ailixed at the under-side of the base member H by a suitable fastening washer ll.

The circular convex housing 22 is further spaced apart from and afiixed to the base I: by the posts 24. As shown in Figure 4 pins 25 project from the housing 22 for releasable engagement with suitable socket portions 28 mounted in the posts 24. whereby the housing 22 may be conveniently removed for repair or adjustment of the control mechanism mounted on the base l2. The posts 24 and socket portions 26 are fastened to the base H by the nuts '5 which screw threadedly engage the socket portions 28 at the under side of the base I2. The space 21 separating. the base member I! from the casing 22 provides for a ready and efficient circulation of air around and adjacent to bimetallic members I and 2 so as to provide for their more emcient response to the temperature thereof.

Further projecting from the bracket 9 at a point adjacent to the bimetallic member 2 are switch supporting arms 28 and 28. .The arms 28 and 29 are connected by a flanged portion 30 to which is riveted the resilient spring blade 2|. Intermediate the opposite ends of the resilient spring blade 3| there is riveted at 32 an arm 33. The arm 33 is bent so as to extend substantially parallel to and at the opposite side of the resilient spring blade 3| from the bimetallic member 2. At one end of the arm I: there is provided a plate member 34 extending at an angle to arm 33 and positioned across spring blade 3| and the bimetallic member 2. The plate 34 is suitably apertured at 35 and It so that the bimetallic member 2 and the spring blade member 2| may conveniently project through the respective apertures and are operatively engaged by inner edges of the said apertures.

As shown in Figures 4. 5 and 8 there is mounted at the free end of the spring blade switch member 3| a contact member 31 for cooperation with a contacting screw member 38. A contact member 39 is further mounted on the arm 33 for cooperation with a switch contact screw 40. The switch contact screw 40 is suitably connected by a strap 4| to terminal 42, while the screw contact ll is suitably connected by electrical conductor strap 43 to terminal 44.

Positioned intermediate the two bimetallic members and 2 is a heating member 45, best shown in detail in Figure 4. Such heating element is preferably formed of a suitable carbon cylinder having powdered copper sprayed at the opposite ends for contact purposes. One end of the carbon heater 43 engages a portion 41 contact end but extends v thereof. In operation, it

' the heater 45.

hich projects nected to contact 39 a conductor of electrical energy to the opposite terminal of the carbon heater 45. Engaging in electrical conductinglrelation with the said other terminal of the carbon heater 43 and the conductor II is a shield like dampening member 52 which engages the carbon heater" at said other around and is spaced apart from substantially the remaining portion upon the conductors 41 and- 50 becoming energized current will pass through the conductor 53, dampener 52 to one terminal of the carbon heater 45 and then through the carbon heater 45 to the opposite terminal of the heater 45 fromv where it will return to the source of electrical energy through theconductor 41. As shown in Figure 3.

the bracket 3 is suitably bowed at 34 to avoid contacting the surrounding dampener or shield 32 of the strap 55 serves as a the bolt 59 to terminal 53.

In the operation of the foregoing mechanism, the resilient switch blade 3| not only serves as a resilient push-back switch contacting means but the same at exerts a biasing arm 33 which through the engaging plate 34 biases the bimetallic member 2 and accordingly the bimetallic member I in a clockwise direction about the pivotal suitable conductor from surface it of the cam l1. Thus, under the biasing force of the resilient spring blade member 3|, the adjustable screw |5 in normal operation is held at all times in engaging relation with the inclined surface of the cam which the switch mech- It will further be seen sincethe switch contact 31 is arranged so as to engage contact 38,-before contact 39 engages contact 40, that upon contact 31 engaging contact screw of the resilient spring member 3| will cease biasing the bimetallic member 2 in a clockwise direction upon temperature decrease The spring member 3| will then rather counteract such clockwise movement of the member 2 upon the switch member 31 contacting the switch member 38. Thus, where as before, the force of the resilient member 3| tended engagement with the member 33, the said rewill tend to act against the engagement of the member 39 with the member 49. Therefore the spring rate will vary. Thus, it will be readily seen that the resilient spring member 3| will act in two distinctly different capacities, in one case, tending to bias the conthe contact 33 and tact 31 into engagement with in the other case tending to counteract the biasing of the contact 39 into engagement with the contact 40, the purpose of which will be explained.

will thus be seen that a bimetallic member 2,

Further, as shown in Figure 3,

to bias the member 31 into i circuit. Moreover, before the ductor 16 back to In Figureathere issh'own a wire of a circuit employing the thermall responsive switch mechanism of my present invention. A stepdown transformer 34 is used to supply low voltage current to the circuit. The transformer comprises a line voltage primary 35 and a low voltage secondary 39. end of this secondary is conand the other end thereof terminal of a relay coil 93. associtaed with switch arms 63 is connected to one This relay coil is and 10 which are 1| and 12; respectively, upon energization of said coil. Switch arm 19 and contact 12 control the operation of the temperature varying means; thus and contact may control the,

the contact arm operation of an oil burner motor, a gas ,valve or some similar device. Contact 1| is connected to the heater-4i through the terminal 53, as previously described, and the heater is in turn con nected to the resilient spring blade switch arm 3| and arm 33 through the portion 41 of the bracket 9. Contact; 31 and 33, as previously described, are less widely spaced than contacts 39 and4llso that upon a decrease in temperature contacts 31 and 33 are first brought into engagement upon the clockwise movement of the previously described. The bimetallic elements- I and 2 are adapted to cooperate so as to move the switch arms 3| and 33 in the direction of contacts 38 and 40 upon a fall in' temperature. Upon such a fall in temperature taking place, contacts 31 and 33 are firstbrought into engagement. The engagement of these contacts alone does not establish any engagement of the contacts 31 and '39, the contact engaging movement of the bimetallic members and 2 was aided by the biasing force of the resilient member 3| but from this point on engagement of the contacts 39 and 49 is resisted by the biasing force of the spring member 3|. However, if the fall of temperature continues, contacts 39 and 43 will eventually be brought into engagement by reason of the fact that the bimetallic members I and 2 will overcome the biasing force of the resilient spring member 3| and will force the arm 33 through the plate 34 in a direction so as to cause the engagement of contacts 39 and 40. Upon engagement of contacts 39 and 40, the following energizing circuit is established: from secondary 63 through conductor 13, contacts 38 and 31. switch arm 3| and 33, contacts 39 and 40, conductor 14, conductor 15, relay coil 68, and conthe secondary 63. The establishment of this energizing circuit results in relay coil 63 being energized and causing the engagement of contact arms 69 and 10 with contacts 1| and 12, respectively. The engagement of switch arm 10 with contact 12 completes the circuit of the temperature varying means. The engagement of contact arm 69 with contact 1| establishes a holding circuit for relay coil 68. This holding circuit is as follows: from secondary 63 through conductor 13, contacts 38 and 31, switch arm 3|, bracket 9, heater 45, cap 52, screw 50, member 55, conductor 11, contact 1|, and switch arm 63, conductor 15, relay coil 68, conductor 16, back to the secondary 66. Thus, so long as both contacts 33 and 31 and contacts 39 and 40 are in engagement there will be two pair of circuits through coil 68, one the heating element circuits being merely portion of the switch across the contact carrying mechanism. Since the foradapted to engage with contacts of these circuits including Q 45 and the other of these oi the presence of the high resistance carbon heating element 45, very little current will flow through this circuit. As the temperature of the space to be heated rise due to the operation 01 the temperature varying means, the bimetallic members I and 2 will be gradually deflected in that direction tending to move contacts 09 and 31 away from contacts 40 and respectively, and the movement of the bimetallic members I and 2 in this direction will be aided by the biasing force of the spring member 0|. Aiter this connection has continued for a short time, contacts 39 and 40 which, as previously mentioned, are more widely spaced than contacts 31 and 30 will be moved out of engagement leaving contacts 31 and 38 still in engagement. I! this takes place the only circuit through relay coil 60 is through the heater 45 so that greater electrical energy will now flow through the heater. This will cause the heating element 45 to raise the temperature adjacent the bimetallic elements I and 2 with the result that within a comparatively short period of time the bimetallic elements I and 2 will be deflected suillciently in response to the increased temperature to overcome the biasing iorce oi! the spring member 3| suiilciently so that the disengagement of contacts 31 and 30 will finally be effected. It will be seen that the eflect of the heater 45 is toaccelerate the breaking of the contacts of the thermostatic switch after the temperature in the space has begun to rise by reason of the operation of the temperature varying means. By reason of the sequential engagement of contact 31 and 08 and 30 and 40, a chattering action is avoided in that very slight movement of the bimetallic elements I and 2 will not put into operation the temperature varying means, nor after both pairs of contacts are in engagement will a slight temporary rise sumcient only to cause disengagement of contacts 09 and 40 momentarily, cause the temperature varying means to be put out of operation. However, when the rise in temperature is not merely a temporary one but i indicative of gradually risin temperature by reason of the operation of the temperature varying means, .the heater 40 functions to cause a more rapid disengagement of the temperature responsive switch mechanism so as to lessen the danger of temperature rising above the optimum temperature. It will thus be seen that this operation is materially aided by the novel spring biasing means 3| which aids in the biasing of contacts 31 and 30 into engagement in the first step of the operation and counteracts or acts against the engagement of the contacts 39 and 40 in the second step of the operation. Similarly, in reverse operation it will be seen that the novel spring means SI aids the breaking of the contacts 39 and 40 in the first step of the reverse operation but tends to counteract the biasing force of the bimetallic elements I and 2 in the opening of contacts 01 and 30 in the second step of the reverse operation. Thus in both actions the spring means 3| acts against the actuation of the vital second step or the operation.

If means such as described are not provided, itis quite common iorthe temperature to rise a number of degrees above the desired temperature after the temperature responsive control mechanism has put into operation the temperature varying means, due to the time lag between the projection of the heat in the furnace and the delivery of the same to the room or space to be heated.

Furthermore it will be seen that I have provided a novel compact housing for the temperature responsive mechanism, which mechanism may be mounted on the wall or the surface of the room to be heated. Further, as shown in Figure 1 the temperature responsive mechanism may be readily adjusted for the condition value at which the temperature varying means is to be operated by the simple adjustment of the disk 2I. A pointer 50 is mounted on the disk 2| for cooperation with suitable indications 62 provided on the casing 22 for indicating the desired temperature. In Figures 2 and '7, there is shown a modified form of casing tor my condition responsive mechanism. This form of my control mechanism diiiers structurally from the previously described form primarily in the arrangements of the manual adjustment means, Instead of the cam I1 being adjusted by the disk 2I through the shaft I0, I have provided in the modified form of my invention an adjustable annular member I00 for regulating the position of the cam I1. A fixed post I0l projects from the be: I2 and has rotatably mounted thereon the cam I1.

A convex shaped circular casing I04 is provided mounted upon the base member I2 by posts 24. Pin members 20 are provided adapted to be disposed in suitable apertures formed in the socket portions 20 arranged as previously described so that the casing I00 may be conveniently removed for repairs and adjustments 0! the mechanism contained therein.

At the apex oi the covering I" an annular opening I00 is provided within which is disposed annular adjustment means I00 fastened by tongue members I01 in engaging relation with a rotatable shaft I00 projecting from the cam member I! and surrounding the fixed shaft Ill.

An annular recess I00 is formed within the member I00 for receiving a fixed disk like member I02 having a fixed shalt III projecting through a suitable aperture formed in the member I00. The shaft H3 is fastened by tongue members I00 to the post IOI fixedly mounted on the base member I2. The shaft I I3 and the fixed member IOI are further secured together by isstening bolt I I0.

A cap like member Ill formed of Lucite or other suitable transparent plastic material is placed over the disk I02. The cap like member III has provided a projecting annular flange III separating the annular edge of the disk I02 from the corresponding inner annular edge of the member I00. A split spring ring H5 positioned within a suitable annular groove formed at the inner edge of the fiange II9 secures the transparent cap I I4 on the disc member I02. A monogram card or other suitable identification means IIB may be placed between the disk I02 and the transparent cap III so as to show through the transparent cap I as shown in Figure 7.

A leaf spring III is disposed between the bottom of the disk I02 and an edge II2 defining the bottom of the annular recess I06 01! the adjustment member I00 within which the disk I02 is disposed. The said leaf spring III is arranged so as to bias the annular member I00 toward the base I2 and serves as a slip friction arrangement whereby the adjustment member I00 may be held in adjusted position.

The outer annular edge of the adjustment member I00 is knurled at III whereby the same may be conveniently adjusted with the finger tips causing thereby a corresponding adjustment of has been provided 'dition fluctuations.

the cm I! and accordingly adjusting the control mechanism as previously explained, An indicator mark ill is provided on the knurled edge. I I! for cooperation with suitable scale markings I28 provided on the casing I for indicating the condition value at which the temperature varying means is to be operated by the control mechanism.

As shown in Figure 2 there is further provided in the casing I04 a semi circular slot I behind which is fastened by suitable means a semi circular thermometer tube III preferably of the mercury type having an indicator line III which is arranged to show through the slot I20 and cooperate with the said scale markings I23 so as to indicate the temperature of the air adjacent thereto.

It will be seen from the foregoing that there a condition responsive control mechanism of very compact structure and arrangement, in which there is included a pair of U-shaped bimetallic members so arranged that the same may be confined in a very limited space while the totality of the efiect thereof in accuracy and efiiciency is equal to that of a single bimetallic strip having a length equal to the sum of the lengths of the pair of U-shape bimetallic members. Moreover there is provided a novel casing of a hemispherical shape for housing this compact structure, including a novel finger tip adjustment means. Such casing further provides an annular opening surrounding the condition responsive mechanism and immediately adjacent thereto for the better circulation of the surrounding medium so as to cause the immediate response of such mechanism to condition variation. Further, I have provided a novel switch mechanism in which a push back resilient spring blade switch member serves as a means for initially biasing the bimetallic members and for'exerting a force having the double efiect of acting against change in a condition varying means from first an operatlve to an inoperative state and second from an inoperative to an operative state. thereby preventing such changes due merely -to slight con- I have further provided within the said housing a compact novel heater arrangement having great eillciency in comparison to its sizeior anticipating the arrival of the condition varying medium called for by the condition responsive switch mechanism.

While two specific embodiments of this invention have been described, it will be understood that these are for the purpose of illustration only, and that the invention is to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a device of the character described, comprising in combination, a first control means, a second control means, means for successively actuating the first and then the second control means, biasing means opposing the actuation of the second control means, said actuating means being arranged so as to successively discontinue the-actuation oi the second and then the first control means and said biasing means so arranged as to oppose the discontinuance of the actuation of the first control means.

2. A thermostatic control means, comprising, in combination, a bimetallic element, an actuating arm, means biasing said arm into engagement with said element in such a manner as to bias said element, means limiting the biasing of said bimetallic element by said means, and a control means actuated by said am upon movement of said bimetallic element in response to a change in temperature.

3. A thermostatic control means, comprising, in combination, a bimetallic element, an arm engaging said bimetallic element, a leaf spring engaging said arm and biasing said element in one direction, stop means limiting the biasing of said element by said leaf spring in said one direction, first control means actuated by said leaf spring upon movement of said bimetallic element in said one direction upon temperature change, and second control means actuated by said arm upon additional movement of'said bimetallic element in said one direction, and said leaf spring arranged in such a manner as to exert a biasing force upon said arm on said additional movement of said element so as to oppose said additional movement of said arm in said one direc- 4. A thermostatic switch comprising in combination, a bimetallic element, a first switch arm, a second switch arm, said second switch arm biased into engaging relation with said first switch arm under a first condition and said second switch arm biasing said first switch arm into engaging relation with said bimetallic element under a second condition, a first fixed switch contact for engagement with said first switch arm and a second fixed switch contact for engagement with said second switch arm, said switch contacts so arranged that upon movement of said bimetallic element upon temperature change said second switch contact may be engaged by said second switch arm prior to engagement of said first switch contact by said first switch arm, and said second switch arm biased for engaging said second switch contact under said first condition and said second switch arm biased so as to oppose the engagement of said first switch contact by said first switch arm after the engagement of said second switch contact by said second switch arm.

5. A control switch, comprising, in combination, a first fixed contact, a second fixed contact, movable contacting means for cooperating with the said fixed contacts, condition responsive means for actuating the said contacting means. the said contacting means arranged for engaging successively the first contact and then the second contact and disengaging in succession first the second contact and then the first contact, and biasing means for opposing the said engagement of the second contact and the said disengagement of the first contact.

6. A thermostatic switch comprising, in combination, a pivoted supporting member, a pair of U-shaped bimetallic elements, each element having one end attached to said member, a first switch arm, a second switch arm, said second switch arm being biased into engaging relation with said first switch arm and biasing said first switch arm in such a manner as to cause the biasing of said first switch arm into engaging relation with one of said bimetallic elements so as to bias said supporting member for rotation about said pivot, stop means for engaging the other of said elements so as to limit rotation of said supporting means in response to the'biasing force exerted by said second switch arm, a first fixed contact for engagement by said first switch arm and a second fixed contact for engagement by said second switch arm upon'movement-in one direction of said bimetallic elements switch means, supporting means ior mounting.

said cover on said base in spa ed relation to said base whereby there is provided an opening surrounding said temperature responsive means so that air may circulate through said opening directly adjacent to said temperature responsive means, a. disk mounted substantially at the apex of said cover and iorming a part oi said cover, said disk aiiixed to said base, a ring like member surrounding said disk and manually adjustable for regulating the temperature condition at which said temperature responsive means may control said switch means.

8. A thermostatic switch comprising, in combination, a base, a bracket aillxed to said base, a pair oi bimetallic elements, said elements connected at one end, and said connected elements pivotally mounted on said bracket, said elements being positioned side by side in spaced relation and extending laterally from said pivotal mounting, control means operated by the other end oi one of said pair oi elements, a rotatable cam positioned within the space separating the said elements and having the axis thereoi extending transverse to the axis oi the pivotal mounting oi said elements, said cam operably engaging the other end of the second oi said pair oi elements in order to adjust the temperature value at which said thermostat is set.

9. A thermostatic switch com rising, in combination, a base, a bracket aiiixed to said base, a member pivotally mounted on said bracket, a pair of U-shaped bimetallic elements, each element attached at one end to said member, said elements being positioned side by side in spaced relation and extending laterally thereirom, control means operated by the other end oi one of said pair of elements, a cam rotatably mounted intermediate the said pair oi U-shaped bimetallic elements and arranged ior moving the other end of the second oi said pair oi elements in order to adjust the temperature value at which said thermostat is set.

10. A thermostatic switch comprising, in combination, a base, a bracket, affixed to said base, a member pivotally mounted on said bracket, a pair of U-shaped bimetallic elements, each element attached at one end to said member, said elements being positioned side by side in spaced relation and extending laterally thereirom, a fixed contact, a spring blade biasing said member ior rotation about said pivot and the spring blade operated by the other end i one oi said pair oi elements for cooperating with said fixed contact for controlling an electrical circuit, a cam rotatably mounted between said pair of U-shaped bimetallic elements and arranged so as to engage the other end of the second oi said pair of elements soas to adjustably limit the rotation oi said member in response to the biasing iorce oi said spring blade, and said cam arranged so as to adjustably position said spring blade in relati n to said fixed contact in order to adjust the change, and said secmeans in such a manner accusetemperature value at which said thermostat is set. i

11. A thermostatic switch comprising, in combination, a base, a bracket aifixed to said base. a member pivotally mounted on said bracket, a pair oi bimetallic elements, each element attached at one end to said member, said elements being positioned side by side in and extending laterally thereirom, operated by the other end oi one oi said pairs oi elements, adjusting means cooperating with the other end oi the second oi said pair oi elements, an auxiliary heat producing means positioned within thev space separating the pair oi elements and said auxiliary heat producing means substantially equally distanced irom said elements so that the heat produced thereby may substantially equally aiiect said elements, and said auxiliary heat producing means regulated by said control means.

12. A therm tatic control ior regulating the heating medium supplied irom a main source, comprising, in combination, a temperature responsive means, control means operated by said temperature responsive means, a cylindrical carbon block having an aperture iormed therein and extending therethrough, a first electrical conductor engaging said block at one end, a second electrical conductor extending through said aperture in spaced relation to the interior aperture defining wall oi said block and said first conductor, a cylindrical cap like member mounted upon the otherend oi said cylindrical carbon block and electrically connecting said second conductor andsaid other end oi said carbon block, said cap like member surrounding in spaced relation a portion oi the cylindrical outer wall oi said block, said conductors connected in an electrical circuit ior energizing said carbon block ior the production oi an auxiliary supply oi heating medium, said cap like member regulating the radiation oi said heating medium, and said electrical circuit controlled by said control means, whereby upon a predetermined rise in temperature said carbonaceous block will be electrically energized so to cause the production oi said auxiliary supply of heat ior effecting said temperature responsive as to anticipate the arrival oi an additional supply oi heating medium irom said main source and causing said temperature responsive means to operate said control means ior periorming an additional control iunction.

13. A device of the character described, comprising, in combination, a base, a first bracket afilxed to said base, a second bracket pivotally mounted on siad first bracket, a pair of U-shaped bimetallic elements, each element attached at one end to said second bracket, said elements being positioned side by side and in spaced relation extending laterally therefrom, the high expansion portions oi said elements being-reversed with respect to each other, a first switch arm, a second spring blade switch arm, said second switch arm biasing said first switch arm into engaging relation with one of said bimetallic elements in such a manner as to bias said second bracket ior rotation about said pivot, a first switch contact for engagement by said first switch arm and a second switch contact for engagement by said second switch arm, a cam having an inclined surface, said cam mounted on the base within the space separating the said pair oi bimetallic elements and the inclined surface oi said cam arranged for engaging the other spaced relation control means end of the second of said pair of elements to adjustably limit the rotation of said second bracket in response to the biasing force of said second switch arm, and said inclined surface of said cam so arranged as to adjust said element so as to adjustably position said switch arms in relation to said switch contacts in order to adjust the temperature value at which said contacts may be engaged by said switch arms, an electric heater mounted on said first bracket and positioned between and spaced substantially an equal distance apart from each of said bimetallic members, and said electric heat controlled by said first and second switch arms whereby upon a predetermined rise in temperature said electric heater will be electrically energized so as to cause soas' the production of an auxiliary supply of heating medium for effecting said bimetallic elements so as to anticipate the arrival of an additional supply of heating medium from a main source, a spherical 'cover surrounding said bimetallic elements and switch arms-said spherical cover having a concaved inner surface and a convexed outer surface, supporting members for ailixing said cover on said base in spaced relation to said base whereb there is provided an opening surrounding said bimetallic elements for the free passage of air through said opening directly ad- Jacent to said bimetallic elements, an annular adjustment means rotatably mounted substantially concentric with the apex of said convexed outer surface of said cover, and said annular adjustment means mechanically connected to said cam for the adjustment thereof, and indicator means provided on said cover forcooperation with said annular adjustment means so as to indicate the temperature value at which said device is set.

14. A thermostatic switch comprising in combination, elements, each of said elements bent transversely at a portion intermediate the ends thereof, each of said bimetallic elements pivotally attached at one end to said base and said bimetallic elements mechanically interconnected, control means operated by the other end of one of said bimetallic elements in response to the joint temperature responsive movement of both of said elements, stop means for engaging the other end of the second of said pair of bimetallic elements, and biasing means for initially moving said himetallic elements in such a manner as to pivot said second bimetallic element into engaging relation with said stop means.

15. A thermostatic switch comprising, in combination, a base, a pair of U-shaped bimetallic elements, each of said U-shaped bimetallic elements pivotally fastened at one end on said base, a switch mechanism operated by the other end of one of said U-shaped bimetallic elements, adiustable stop means for engaging the other end of the second of said pair of U-shaped bimetallic elements, spring means for pivoting said second u-shaped bimetallic element in such a manner as to engage said adjustable stop means, and said U-shaped bimetallic elements mechanically connected in such a manner that upon temperature change the resulting movement of said other end of said one U-shaped bimetallic element will be in an amount equal to the sum of the temperature responsive movements of each of said himetallic elements.

16. A thermostatic control means, comprising, in combination, a bimetallic element, an arm engaging said bimetallic element, a spring engaga base, a pair of elongated bimetallic lug said arm and biasing said element in one direction, first control means actuated by said spring upon movement of said bimetallic element in one direction upon temperature change, and second control means actuated by said arm upon additional movement of said bimetallic element in said one direction, and said spring arranged in such a manner as to exert a biasing force upon said arm on said additional movement of said element so as to oppose said additional movement of said arm in said one direction.

17. A thermostatic control means, com rising, in combination, a bimetallic element, an arm engaging said bimetallic element, a spring means engaging said arm and biasing said element in .one direction, a variable stop means limiting the biasing of said element by said spring in said one direction, means for adjusting said variable stop means, first control means actuated by said spring means upon movement of said bimetallic element in said one direction upon temperature change, and second control means actuated by said arm upon additional movement of said bimetallic element in said one direction, and said spring arranged in such a manner as to exert a biasing force upon said arm on said additional movement of said element so as to oppose said additional movement of said arm in said one direction.

18. In a condition responsive device of the class described, in combination, a round base, a pair of side by side elements connected in tandem mounted on said base, the high expansion portion of said elements being reversed with respect to each other whereby on a change in a condition the eilects of the pair of elements are additive, adjusting means disposed at the center of the base between the said elements, and a curved cover for the said condition responsive device spaced from said base providing an air passage around the entire periphery of the cover through which air may flow.

19. In a device of the character described, comprising in combination, a first control means, a second control means, means for successively actuating the first and then the second control means, biasing means aiding the actuation of the first control means under a first value of a condition, the biasing means opposing the actuation of the second control means under a second value of the condition, said actuating means successively discontinuing the actuation of the second control means and then the first control means,

the biasing means aiding the discontinuance of actuation of the second control means under a third value of the condition, and the said biasing means opposing the discontinuance of actuation of the first control means under a fourth value of the condition.

20. In a device of the character described, comprising in combination, a. first control means, a second control means, means for successively actuating the first and then the second control means, biasing means aiding the actuation of the first control means under one value of a condition, the biasing means opposing the actuation of the second control means under a second value of the condition, the said actuating means successively discontinuing the actuation of the second control means and then the first control means, the biasing means aiding the discontinuance of actuation of the second control means under a third value of the condition, said biasing means opposing the discontinuance of actuation of the first control means under a fourth value of the condition, and means for adjusting the actuating means. 21. In a device or the character, described, comprising, in combination, a first control means, a second control means, means for successively actuating the first and the second control means, biasing means aiding the actuation of the first control means under one value of a condition, said biasing means opposing the actuation of the second control means under a second value of the condition, the said actuating means successively discontinuing the actuation of the second and then the first control means, the biasing means aiding the discontinuance o! actuation of the second control means under a third value of the condition, said biasing means opposing the discontinuance oi actuation of the first control means under a fourth value 01 the condition, and

means accelerating the discontinuance of actuation of the first control means after the discontinuance of actuation of the second control means.

22. In a device 0! the character described, comprising, in combination, a first control means, a second control means, biasing means opposing the actuation of the second .control means, said cessively discontinue the actuation arranged so as to sueoi the second and then the first control means, said biasing means so arranged as to oppose the discontinuance of the actuation oi the first control means,

and means acceleratins the discontinuance of actuation o! the first control means alter the discontinuance ot actuation of the second control means.

23. A unitary air condition responsive device comprising, in combination, a round base, air condition responsive means mounted upon said base, control means actuated by said air condition responsive means, a circular convex shaped cover (or enclosing said responsive means having its center substantially coinciding with the center of said base, the cover comprising a stationary portion and a rotatable portion having a circular periphery, the axis of rotation oi said rotatable portion coinciding with the center of said cover as a whole, means for mounting said cover on said base, and means actuated by said rotatable cover portion for adjusting the value of the condition at which said air condition responsive means actuates said control means.

CARL G. KRONMIILER. 

